Dear "Morph":
Remember, the dictionaray definition of "allo-" is "one of a set of
similar items together which constitute a structural unit." Now, that
unit can be called a "phoneme" or a "morpheme," and in this way the
structurazation of elements can be understood in the "emic-, etic-"
way Ken Pike had in mind.
Allo Ha,
Hugh Buckingham